Patent GB-782928-A (GB)
Title: Improvements relating to 1.2-alkylene-diamino-n.n-diacetic acids and their salts
Inventor: KNOLL HARRY
Filed: 1955-01-28
Abstract: The invention comprises compounds of the formula <FORM:0782928/IV (a)/1> where R1 to R4 are the same or different and are hydrogen, alkyl or hydroxyalkyl or R1 and R2 or R3 and R4 jointly are a divalent polyalkylene group forming a saturated ring with both the ethylene carbon atoms of not more than 6 carbon atoms, M1 and M2 are hydrogen, alkalimetal, ammonium or monovalent radicals of primary, secondary or tertiary aliphatic amines, M3 and M4 are hydrogen or alkali metal, and where the benzene rings may have one or more, the same or different substituents which do not react with primary amines and are not hydrolysed by acid.  Specified substituents are sulphonic acid, carboxyl, alkyl, alkoxy, nitro, amino, hydroxyl and halogen. The compounds are prepared by treating 1 mol. of a diamine of the formula <FORM:0782928/IV (a)/2> where R1 to R4 have the meaning above with 2 mols. of a substituted or unsubstituted salicylaldehyde, adding hydrocyanic acid to the disalicylidene - 1 : 2 - alkylene diamine formed and saponifying the di-nitrile thus obtained. Diamines specified are ethylene diamine, methyl - 1 : 2 - ethylene diamine, 1 : 2 - dimethyl ethylene diamine, 1 : 2-dihydroxyethylethylene diamine and cyclohexane-1 : 2-diamine. Compounds containing the above-mentioned substituents on the benzene rings are prepared by using correspondingly substituted salicylaldehydes; cyano-salicylaldehydes may also be used, the cyano substituent being hydrolysed to carboxyl at the saponification stage. Sulphonic acid groups may also be introduced into the benzene rings of the compounds of the above general formula by direct sulphonation. Aldehydes specified are salicylaldehyde, and 2-hydroxy - 3 - sulpho -, 2 - hydroxy - 5 - chloro-, 2-hydroxy-3-methoxy-, 2 : 4- or 2 : 6-dihydroxy-, 2 - hydroxy - 3 - cyano -, 2 - hydroxy - 3 - carboxy-, 2 - hydroxy - 3 - or - 5 - amino -, and 2 - hydroxy - 3 - or - 5 - nitro - benzaldehydes. The condensation, HCN addition and saponification are effected by known methods.  Many acids of the above general formula are specified.  The salts may be prepared by direct reaction of the acids with bases in water.  Amine bases specified are mono-, di- and tri-ethanolamine, methyl, ethyl, dimethyl and diethylamine, ethylene diamine, laurylamine and morpholine.  The acids and salts of the above general formula form complex compounds with metals such as ferrous and ferric iron, beryllium and manganese.  In examples: (1) 1 : 2-ethylene-bis-(amino - o - hydroxyphenyl - acetonitrile), prepared by reacting N : N1-disalicylidene ethylene diamine with liquid HCN and HC. in water, is hydrolysed with HCl to a mixture of the hydrochlorides of 1 : 2-ethylene-bis-(amino-o-hydroxyphenyl-acetic acid), of its monoamide and diamide, and of the compound of the formula <FORM:0782928/IV (a)/3> and of its amide, the mixture is dissolved in water and a product consisting chiefly of III is isolated by precipitation with alkali and hydrolysed to 1 : 2-ethylene-bis-(amino-o-hydroxyphenyl-acetic acid) dihydrochloride by heating with concentrated HCl; (2) N : N1-disalicylidene - 1 : 2 - cyclohexanediamine, prepared by reacting 1 : 2-diaminocyclohexane with salicylaldehyde in methanol, is treated with HCN and the product hydrolysed with concentrated HCl to give 1 : 2 - cyclohexane - bis - (amino - o - hydroxyphenyl - acetic acid); (3), in a similar manner methyl - 1 : 2 - ethylene - bis - (amino - o - hydroxyphenyl - acetic acid) is prepared via N : N1-disalicylidene-methyl-ethylene diamine; (4) 1 : 2-ethylene-bis-(amino-o-hydroxy-phenyl-acetic acid) is heated with concentrated sulphuric acid to give 1 : 2-ethylenebis - (amino - 2 - hydroxy - 5 - sulphophenyl - acetic acid).